NAME

gitrevisions - specifying revisions and ranges for Git

SYNOPSIS

gitrevisions

DESCRIPTION

Many Git commands take revision parameters as arguments. Depending on
the command, they denote a specific commit or, for commands which
walk the revision graph (such as git-log[1]), all commits which can
be reached from that commit. In the latter case one can also specify a
range of revisions explicitly.

In addition, some Git commands (such as git-show[1]) also take
revision parameters which denote other objects than commits, e.g. blobs
("files") or trees ("directories of files").

SPECIFYING REVISIONS

A revision parameter <rev> typically, but not necessarily, names a
commit object. It uses what is called an extended SHA-1
syntax. Here are various ways to spell object names. The
ones listed near the end of this list name trees and
blobs contained in a commit.

<sha1>, e.g. dae86e1950b1277e545cee180551750029cfe735, dae86e

The full SHA-1 object name (40-byte hexadecimal string), or
a leading substring that is unique within the repository.
E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both
name the same commit object if there is no other object in
your repository whose object name starts with dae86e.

<describeOutput>, e.g. v1.7.4.2-679-g3bee7fb

Output from git describe; i.e. a closest tag, optionally
followed by a dash and a number of commits, followed by a dash, a
g, and an abbreviated object name.

<refname>, e.g. master, heads/master, refs/heads/master

A symbolic ref name. E.g. master typically means the commit
object referenced by refs/heads/master. If you
happen to have both heads/master and tags/master, you can
explicitly say heads/master to tell Git which one you mean.
When ambiguous, a <refname> is disambiguated by taking the
first match in the following rules:

If $GIT_DIR/<refname> exists, that is what you mean (this is usually
useful only for HEAD, FETCH_HEAD, ORIG_HEAD, MERGE_HEAD
and CHERRY_PICK_HEAD);

otherwise, refs/<refname> if it exists;

otherwise, refs/tags/<refname> if it exists;

otherwise, refs/heads/<refname> if it exists;

otherwise, refs/remotes/<refname> if it exists;

otherwise, refs/remotes/<refname>/HEAD if it exists.

HEAD names the commit on which you based the changes in the working tree.
FETCH_HEAD records the branch which you fetched from a remote repository
with your last git fetch invocation.
ORIG_HEAD is created by commands that move your HEAD in a drastic
way, to record the position of the HEAD before their operation, so that
you can easily change the tip of the branch back to the state before you ran
them.
MERGE_HEAD records the commit(s) which you are merging into your branch
when you run git merge.
CHERRY_PICK_HEAD records the commit which you are cherry-picking
when you run git cherry-pick.

Note that any of the refs/* cases above may come either from
the $GIT_DIR/refs directory or from the $GIT_DIR/packed-refs file.
While the ref name encoding is unspecified, UTF-8 is preferred as
some output processing may assume ref names in UTF-8.

@

@ alone is a shortcut for HEAD.

<refname>@\{<date>\}, e.g. master@{yesterday}, HEAD@\{5 minutes ago\}

A ref followed by the suffix @ with a date specification
enclosed in a brace
pair (e.g. {yesterday}, \{1 month 2 weeks 3 days 1 hour 1
second ago\} or \{1979-02-26 18:30:00\}) specifies the value
of the ref at a prior point in time. This suffix may only be
used immediately following a ref name and the ref must have an
existing log ($GIT_DIR/logs/<ref>). Note that this looks up the state
of your local ref at a given time; e.g., what was in your local
master branch last week. If you want to look at commits made during
certain times, see --since and --until.

<refname>@\{<n>\}, e.g. master@{1}

A ref followed by the suffix @ with an ordinal specification
enclosed in a brace pair (e.g. {1}, {15}) specifies
the n-th prior value of that ref. For example master@{1}
is the immediate prior value of master while master@{5}
is the 5th prior value of master. This suffix may only be used
immediately following a ref name and the ref must have an existing
log ($GIT_DIR/logs/<refname>).

@\{<n>\}, e.g. @{1}

You can use the @ construct with an empty ref part to get at a
reflog entry of the current branch. For example, if you are on
branch blabla then @{1} means the same as blabla@{1}.

@\{-<n>\}, e.g. @\{-1\}

The construct @\{-<n>\} means the <n>th branch checked out
before the current one.

<branchname>@{upstream}, e.g. master@{upstream}, @{u}

The suffix @{upstream} to a branchname (short form <branchname>@{u})
refers to the branch that the branch specified by branchname is set to build on
top of. A missing branchname defaults to the current one.

<rev>^, e.g. HEAD^, v1.5.1^0

A suffix ^ to a revision parameter means the first parent of
that commit object. ^<n> means the <n>th parent (i.e.
<rev>^
is equivalent to <rev>^1). As a special rule,
<rev>^0 means the commit itself and is used when <rev> is the
object name of a tag object that refers to a commit object.

<rev>~<n>, e.g. master~3

A suffix ~<n> to a revision parameter means the commit
object that is the <n>th generation ancestor of the named
commit object, following only the first parents. I.e. <rev>~3 is
equivalent to <rev>^^^ which is equivalent to
<rev>^1^1^1. See below for an illustration of
the usage of this form.

<rev>^\{<type>\}, e.g. v0.99.8^{commit}

A suffix ^ followed by an object type name enclosed in
brace pair means dereference the object at <rev> recursively until
an object of type <type> is found or the object cannot be
dereferenced anymore (in which case, barf).
For example, if <rev> is a commit-ish, <rev>^{commit}
describes the corresponding commit object.
Similarly, if <rev> is a tree-ish, <rev>^{tree}
describes the corresponding tree object.
<rev>^0
is a short-hand for <rev>^{commit}.

rev^{object} can be used to make sure rev names an
object that exists, without requiring rev to be a tag, and
without dereferencing rev; because a tag is already an object,
it does not have to be dereferenced even once to get to an object.

rev^{tag} can be used to ensure that rev identifies an
existing tag object.

<rev>^\{\}, e.g. v0.99.8^\{\}

A suffix ^ followed by an empty brace pair
means the object could be a tag,
and dereference the tag recursively until a non-tag object is
found.

<rev>^\{/<text>\}, e.g. HEAD^{/fix nasty bug}

A suffix ^ to a revision parameter, followed by a brace
pair that contains a text led by a slash,
is the same as the :/fix nasty bug syntax below except that
it returns the youngest matching commit which is reachable from
the <rev> before ^.

:/<text>, e.g. :/fix nasty bug

A colon, followed by a slash, followed by a text, names
a commit whose commit message matches the specified regular expression.
This name returns the youngest matching commit which is
reachable from any ref. If the commit message starts with a
! you have to repeat that; the special sequence :/!,
followed by something else than !, is reserved for now.
The regular expression can match any part of the commit message. To
match messages starting with a string, one can use e.g. :/^foo.

<rev>:<path>, e.g. HEAD:README, :README, master:./README

A suffix : followed by a path names the blob or tree
at the given path in the tree-ish object named by the part
before the colon.
:path (with an empty part before the colon)
is a special case of the syntax described next: content
recorded in the index at the given path.
A path starting with ./ or ../ is relative to the current working directory.
The given path will be converted to be relative to the working tree’s root directory.
This is most useful to address a blob or tree from a commit or tree that has
the same tree structure as the working tree.

:<n>:<path>, e.g. :0:README, :README

A colon, optionally followed by a stage number (0 to 3) and a
colon, followed by a path, names a blob object in the
index at the given path. A missing stage number (and the colon
that follows it) names a stage 0 entry. During a merge, stage
1 is the common ancestor, stage 2 is the target branch’s version
(typically the current branch), and stage 3 is the version from
the branch which is being merged.

Here is an illustration, by Jon Loeliger. Both commit nodes B
and C are parents of commit node A. Parent commits are ordered
left-to-right.

SPECIFYING RANGES

History traversing commands such as git log operate on a set
of commits, not just a single commit. To these commands,
specifying a single revision with the notation described in the
previous section means the set of commits reachable from that
commit, following the commit ancestry chain.

To exclude commits reachable from a commit, a prefix ^
notation is used. E.g. ^r1 r2 means commits reachable
from r2 but exclude the ones reachable from r1.

This set operation appears so often that there is a shorthand
for it. When you have two commits r1 and r2 (named according
to the syntax explained in SPECIFYING REVISIONS above), you can ask
for commits that are reachable from r2 excluding those that are reachable
from r1 by ^r1 r2 and it can be written as r1..r2.

A similar notation r1...r2 is called symmetric difference
of r1 and r2 and is defined as
r1 r2 --not $(git merge-base --all r1 r2).
It is the set of commits that are reachable from either one of
r1 or r2 but not from both.

In these two shorthands, you can omit one end and let it default to HEAD.
For example, origin.. is a shorthand for origin..HEAD and asks "What
did I do since I forked from the origin branch?" Similarly, ..origin
is a shorthand for HEAD..origin and asks "What did the origin do since
I forked from them?" Note that .. would mean HEAD..HEAD which is an
empty range that is both reachable and unreachable from HEAD.

Two other shorthands for naming a set that is formed by a commit
and its parent commits exist. The r1^@ notation means all
parents of r1. r1^! includes commit r1 but excludes
all of its parents.

To summarize:

<rev>

Include commits that are reachable from (i.e. ancestors of)
<rev>.

^<rev>

Exclude commits that are reachable from (i.e. ancestors of)
<rev>.

<rev1>..<rev2>

Include commits that are reachable from <rev2> but exclude
those that are reachable from <rev1>. When either <rev1> or
<rev2> is omitted, it defaults to HEAD.

<rev1>...<rev2>

Include commits that are reachable from either <rev1> or
<rev2> but exclude those that are reachable from both. When
either <rev1> or <rev2> is omitted, it defaults to HEAD.

<rev>^@, e.g. HEAD^@

A suffix ^ followed by an at sign is the same as listing
all parents of <rev> (meaning, include anything reachable from
its parents, but not the commit itself).

<rev>^!, e.g. HEAD^!

A suffix ^ followed by an exclamation mark is the same
as giving commit <rev> and then all its parents prefixed with
^ to exclude them (and their ancestors).